Mechanical movements



1947- T. H. THOMPSON MECHAN ICAL MOVEMENTS 4 Sheet-Sheet, 1

'Filed July 9, 1945 .[fivenivr TOM H. THOMPSON 2;; 7:219 aiiaf'neys Jan.7, 1947. t 'T, H THOMPSQ 2,414,003-

MECHAN I CAL MOVEMENTS 1947- T. H. THOMPSON. 2,414,003

MECHANICAL MOVEMENiS Filed July 9, 1943 4 Sheets-Shet 3 Jan. 7, 1947. T.H. THOMPSON MECHANICAL MOVEMENTS Filed July 9, 1945 4 Sheets-Sheet 4 TOMH. THOMPSON 6y kzls azivrneys Patented Jan. 7, 1947 MECHANICAL MOVEMENTSTom H. Thompson, Larchmont, N. Y., assignor to Builder-ThompsonEngineering and Research Corporation, New York, N. Y., a corporation ofMichigan Application July 9, 1943, Serial No. 494,071

8 Claims. (Cl. 74-571) This invention relates to mechanismand methodadapted to convert rotary motion to or from reciprocatory motion bymeans of a straight-line motion, i. e., the motion of a connecting rodof theoretically unlimited length. The mechanism is of a type in whichtwo circular eccentrics, one inside the other, are employed to cause theconversion. The object of the invention is to obtain adjustment of thelength of the reciprocatory movement in a simple manner. It ischaracteristic of the invention that each of the two circular eccentricsabove mentioned is itself divided into two eccentrics of equal lift andthat the opposite rotation of the eccentrics in a pair gives the changein length of the reciprocatory motion while simultaneously therelatively opposed rotation of the inner and outer pairs of eccentricscauses-translation of the reciprocatory motion into rotary motion. It isalso characteristic of the preferred form of the invention that when thelift of one of the eccentrics is changed, the lift of the othereccentric automatically adjusts itself to equality.

In my Patent No. 2,316,114, dated April 6, 1943, for a Machine element,there is shown a mechanism for translating rotary motion to or fromreciprocatory motion by means of a straight-line movement whichtheretofore had been obtained by the well-known Scotch yoke. The twocircular eccentrics, one inside the other, of that prior patent areembodied in the present invention, which may be considered animprovement upon that earlier invention. The subjects-matter of mypending-applications Ser. No. 481,336, filed.

March 31., 1943, and. Ser. No. 403,896, filed July 24, 1941, are alsoembodied in the mechanism shown in the present application.

' 'In straight-line motion mechanisms in which two circular eccentrics,one inside the other, are employed in connection with the conversion ofrotary motion to or from reciprocatory motion,

.the two eccentrics revolve in opposite directions to give thereciprocatory motion. In the present specification the elements which goto make up the inner eccentric will be termed the primary eccentricassembly, and the elements which go to make up the outer eccentric willbe termed the secondary eccentric assembly. The two eccentrics cooperatetogether to accumulate the total lift. The movement of each assembly asa unit with relation to the other assembly should be distinguishedcarefully in function from the movement of the elements within oneassembly with relation to each other. in obtaining the variations inlength of the part of the reciprocatory movement contributed by thatassembly. It is this latter type of movement which is the primary objectof the present invention.

In modern engines, pumps, compressors, brakes, torque converters,metering devices or other mechanisms where a mechanical movement such asabove described is used, it is frequently desirable that the length ofthe reciprocatory move ment be variable. In some mechanisms itis evendesirablethat the direction of an oscillation be reversed, as far asconcerns its'timed relation to the rotary movement. If, for example, amechanism of this type were employed in a pump, the time of projectionof the pistons could sometimes be changed to advantage so as to causethe pump to push the water or other liquids in the reverse directionwithout stopping the drive of the-pump. Again, if the mechanicalmovement were em-jployed in a device such as an airplane engine, itwould be possible to change the direction of rdtation of the propellerwithout stopping the engine. In the mechanism which I employ, the sameelements which give the reciprocation are progressively used to reducethe lift or reciprocation to zero and then to increase the lift in theopposite direction. As shown, for example, in my saidprior applicationSer. No. 481,336, the cylinders are arranged in a radial manner in arotor. The rotation of the rotor need be merely relative to the shaftassociated with the primary eccentric-that is to say, it may be theprimary which will do the rotating, and the rotor containing thecylinders may be stationary. The present invention can be employed ineither type of device.

Speaking generally, the present invention contemplates splitting theprimary and secondary eccentric assemblies each into a pair ofeccentrics. Each of these four elements is in itself an eccentricembracing 0r embraced by the companion element with which it goes tomake up one eccentric pair.

In the drawings:

Fig. 1 is a view in elevation, partly broken away, of a rotary pump madein accordance with my invention, viewed from the control end;

Fig. 2 is a view in elevation of the control end plate of the pump ofFig. 1;

Fig. 3 is a view similar to Fig. 2 showing the parts adjusted for fullstroke;

Fig.4 is a vertical view partly in section on th axis of the rotorthrough the pump of Fig. 1, taken on the line 4-4 of Fig. 1;

Fig. 5 is a view in vertical section in a plane normal to the axis ofthe rotor taken on the line 55: of Fig. 4;

Fig. 6 is a view in horizontal section of the pump of Fig. 1, seen alongthe axis of the rotor taken on .the line 6 of Fig. l, with the pump atzero stroke;

Fig. 7 is a view in vertical section similar to Fig. 5, showing theparts in full stroke;

Fig. 8 is a detail view of one piston and cylinder of Fig. '7, atanother rotational position;

Figs. 9 to 11 inclusive show the means articulating the secondaryassembly; Fig, 9 being an end view of the three eccentrics at zerostroke position; Fig. 10 being a view of the parts in side elevation atzero stroke; and Fig. 11 an end elevation of the parts at full'stroke;

Figs. 12 and 13 are diagrammatic views of the movements of theeccentrics and yoke about pump center, Fig. 12 showing the parts at.zero stroke, and Fig. 13 the same parts at the end of a stroke; thesmall dotted circle indicatingpump center.

The invention will be shown and described embodied in a pump, i. e., adevice in which rotary motion is being converted into reciprocatorymotion. In order to simplify the description of the machine, I willfirst describe .the movement of the parts when in motion during constantoperation and while no adjustment of the stroke or lift is being made.Then I will draw attention to the mechanisms and connections which makeit possible'to adjust the stroke.

It should be noted that the movements of the parts are relative and thatwhile in the example shown in the drawings the primary eccentricassembly does not rotate when the machine is merely pumping, thecylinders and pistons rotate. In other words, the device, in analogy tothe terminology for engines, is a rotary pump, i. e., the cylinders andpistons rotate about the pump center and the casing stands still. Theinvention, of course, is equally useful in a radial pump or engine, 1.e., one in which the cylinders do not rotate and the relative motion isobtained by rotation applied at the primary assembly. The principalparts of the easing are the drive end plate 301, the rotor .housing 302and the control end plate 303 (see Fig. 6)

Mounted for rotation about pump center is a rotor 40 in which are sixradial openings constituting the cylinders in which pistons 60reciprocate radially. These Openings are distributed equi-angularlyabout pump center. The rotoris turned by a drive shaft 50 which passesfreelythrough an opening in the drive end plate and is connecteddirectly to the rotor by a flange 402.

The piston 50 in each cylinder is connected to a piston in the cylinderdiametrically opposite to it. forming one unitary element, as can beseen in Fig. 5. As can be seen in this side elevation, the pistons andpiston rods 602 are connected by a yoke 60! and the circular eccentricswhich cause them to reciprocate are located in this yoke. This unitarystructure can be termed the yoke element. The length of the element issuch that when one'piston is fully retracted its mate is fully advanced.There are six istons in the preferred embodiment-shown in the drawings.The pistons arearranged in equi angular relation so that the cylinders.in the rotor are 60 apart. If a different number of pistons are used,the angle between two pistons will be different. The number of pistonsshould be even.

It will be seen thatthe yokes Bill and pistons As already mentioned, inthe form of pump shown in the drawings the obtaining of the necessaryreciprocatory motion involves the rotation of the rotor and pistons 00and the holding stationary of the elements which are functionally at theother end of the machine element. These elements are the inner torsionequalizer shaft 10 and the primary inner eccentrics 80, which will bedescribed next.

The eccentrics are divided into two pairs, the inner pair being known asthe primary assembly. In this primary assembly the inner part is turned"inside out in a manner similar to that in which the primary is turnedinside out in my application Ser. No. 403,896, above referred to. Thisis a source of simplicity of construction andwhat is probably even moreimportantcompactness. The primary inner eccentric consists of the round,so-called torsion equalizer shaft 10 held in an eccentric position withrelation to pump center by two inner eccentrics 80 which support it atits ends. These two eccentrics 80 are keyed on the shaft 10 and are heldin position by roller bearings 80! (Fig. 6) which in turn are supportedby the end plate 305 and flange 402. The end plate 305 at the controlend of the housing is bolted to the housing end plate 303 and can beseen in Figs. 2, 3, 4 and 6. Except when the stroke of the pump is beingadjusted, there is no movement of the roller bearings BM in thestationary end plate 305. The flange 402 supporting the eccentric 80 atthe drive end of the housing is bolted to the rotor 40 and the driveshaft and rotates with them. There are roller bearings 403 between .theouter shoulder of the flange 402 and the stationary drive end plate 3!"of the casing. The means for adjusting the stroke and which keeps theinner primary eccentric from turning at other times will be describedlater.

In the so-called reversal of the primary inner eccentric, the smalltorsion shaft 10 occupies only a. minimum diameter which makes itpossible to have the primary outer eccentric 9E3 lie within the radialdimensions of theeccentrics 60. This outer eccentric 90 extends thecomplete distance between the two eccentrics and, like the eccentricsBU-except when the stroke or lift of the pump is being changed (as willbe explained later)--turns with the torsion shaft i0 and the eccentrics80. These elements, by turning ,in the one direction, combine with thesecondary eccentric assembly turning in the opposite direction, to givethe lift or stroke of the pump.

It will be noted that with the primary inner eccentric reversed and theprimary outer eccentric member of straight uniform diameter, theeccentricity 0r lift transmitted to the secondary assembl does not occuraround the center of the internal diameter of the secondary eccentricassembly, where the lobes of the latter element are spaced. When thestroke of the primary is be ing adjusted the torsion shaft 10 .moves upand down a predetermined center line of the pump.

As in the case of the primary eccentric, the secondary eccentric also iscomposed functional- -ly of two main elements-an inner and an outereccentric. The inner part or element of the secondary eccentric may alsobe termed a main cam shaft. In the structure shown in Figs. 5 and 6 ofthe drawings, it is composed of two parts, a single ribbed unitarysleeve I00 and three eccentric lobes i0l for the pairs of pistons spacedaround the element in equi-angular relation. These angularly spacedpistons are about 60 apart, as can also be seen, for example, in myapplication Ser. No. 403,896, above referred to. There is a spacebetween each lobe and its neighbor in which to place articulating disks,to be described later.

In distinction to the inner secondary cam or eccentric cluster I00, theouter eccentrics'for the three pistons are separate from each other andeach surrounds merely its own lobe of the inner part of the secondaryeccentric. These outer eccentrics are designated in the drawings by thereference characters III], III, H2. If desired, roller bearings H3 canbe placed between the outer secondary eccentrics H0, HI, H2 and the yoke6M, and smaller roller bearings I M can be placed between the inner andouter secondary eccentrics.

It will be well at this point to review the general manner of operationof the four eccentrics which constitute the primary and secondaryeccentrics. While each pair of eccentrics can be functionally consideredas one eccentric in certain'respects, I shall call each pair ofeccentrics and associated parts an eccentric assembly. When the strokeis not being changed, 1. e., adjusted or varied, the two eccentrics ofthe primary assembly turn relatively in one direction with a fixed lift,and the two eccentrics of the secondary assembly turn in the oppositedirection with. a

.fixed but equal lift providing the cumulated or total lift. This causesreciprocation of the pistons. As long as one pair of the four eccentricsis so mounted that the eccentrics in that pair are not at liberty toturn with relation to each other,

it has been found that the eccentrics forming the 1 other assembly willnot change their relation to each other. I have discovered that with thestructure shown, despite the lack of direct connection between theparts, the lift of the primary and secondary eccentrics willautomatically maintain equality if the two elements of one eccentric arerotated in opposite directions with relation to each other. Thus, forexample, in the pump shown in the drawings if the parts 80 and 90 of theprimary eccentric are turned slightly in opposite directions from thepositions shown in Figs.

6 and '7, thereby changing the lift of the primary eccentric, thecombined effect of the change in the primary and of the yoke opening 69!is simultaneously to cause the two parts of the secondary eccentric torotate in opposite directions,

thereby equalizing their lift to that of theplimary eccentric. I believeit to be novel to have two cams or eccentrics, one inside the other,rotating in opposite directions to cause reciprocation of a thirdelement, and at the same time to so construct each of those twoeccentrics that the lift of the two eccentrics can be changed while themechanism is continuing to cause reciprocation of the third element, andto do this in such a manner that the machine automatically keeps thelift of the two eccentrics equal.

I will now describe the mechanism which is the direct or primary meansof adjusting or varying the stroke or lift of the pump. The fundamentalrequirement is that the two eccentrics which with their associated partsconstitute the primary eccentric, may be rotated slightly in oppositedirections. Since the two eccentrics are circular ec centrics, it willbe seen that the cumulated lift of the primary will be changed. It willbe changed, for one thing, in the maximum lift to be obtained from theprimary assembly because the high points of the inner and outereccentrics 8 0 and 9B are further separated than heretofore cams andtorsion shaft l3 clockwise. mechanism to do this can be seen in Figs. 2and It may be noted at this point by looking at Fig. 7

order that the reader may not be confused, it is pointed outthat theouter primary eccentric 9! and the elements 10 and 80 composing theprimary inner eccentric are not rotated relatively to each other to givea higher lift than is shown in Figs. '7 and 13, and therefore themaximum theoretical lift of the primary will not occur. The effectivelifts of the inner and outer eccentrics are equal.

Figs. l2and 13 are merely diagrammatic illustrations of the positions ofthe eccentrics and yokes at zero and full stroke of the embodiment ofthe invention shown in the drawings. These correspond to Figs. 9 and 11.The small dotted circle in each case is pump center and the smallestsolid circle is the position of the inner torsion equalizer shaft 10 andof the inner primary eccentrics 80.

As already referred to, in the example shown in the drawings, the manualadjustment of the stroke of the pump is obtained by movement of theprimary eccentric assembly only. The parts about to he described can beseen best in Figs. 1 to 4, and in Fig. 6. The manual adjustment isrotational in a plane normal to the drive shaft 50 and it iscontrollably obtained by rotation of the hand-wheel fill located on theupper end of a worm screw shaft 102 carried by a bracket 1&3

mounted on the outer end of the flange 364 on the control end plate 393(Fig. 4). The rotation of the worm screw shaft 102 is translated intoverti cal movement by means of a primary control block 164 threaded ontheworm screw shaft and guided vertically by the bracket 563. This blockis connected to the inner and outer eccentrics of the primary eccentricassembly by two arms 1'65, 106 which extend laterally on opposite sidesof the screw shaft M2 at a level approximately opposite the center ofthe drive shaft 5%. Each of these arms provides the necessary turningadjustment for one of the eccentrics of the primary assembly. Theangular movement of the eccentrics caused by these arms is equal. Thusthe arm at the left of the screw shaft m2, as viewed in Fig. 1, connectswith the outer primary eccentric 9i] and the right arm 16% serves toturn the inner eccentric cam 3&1 and torsion shaft H1. As can be seen inthe vertical sectional view, Fig. 6, the left arm Hi5 has a horizontalslot 10? in which slides the outer end of a pin Hill mounted in a collar139 which fits around the outer eccentric 99 and is keyed thereto by keyl iii. There is an open slot H5 in the end plate 335 to permit themovement of the pin F98 without conflict with the end plate. It will beseen that unless the screw shaft 702 is turned, the primary controlblock Hi4, arm Hi5, collar led and key Hi3 will serve to hold the outerprimary eccentric 99 against rotation, but that if the screw is turned,the resultant raising or lowering of the arm Hi5 will rotatetheeccentric. Lowering of the control block H14 will turn the eccentriccounterclockwise, as viewed in Fig. 1. Correspondingly, lowering of thecontrol block 164 will serve to turn the The '3 and in the .upperright-hand corner of Fig. 6.

There is a slot 10? in the arm 106 corresponding to the slot in the arm195 and moving horizontally in that slot H3! is a pin l'l I fastened inthe end of an arm H2 (see Figs. 2 and 3). This arm is mounted on the endof the torsion shaft '10 by a screw l 53 and is locked to the cam 80 atthe right end of the machine by a pin 1 it (see Fig. 6). The screw 7 I3and the pin H4 are on opposite sides of pump-center and swingingthe arm1 I 2 causes rotation of the cam 89 and the torsion shaft 10 anequi-angular amount. The cam 80 at the other end of the torsion shaft isrigidly fastened on the shaft and therefore turns with the shaft and thefirst-mentioned cam 80. In Figs. 1, 2, 4 and 5 the parts are shown setat zero, the position in which no lift is caused by turning of the rotor40. In Fig. 3 the block 194 is shown lowered to the maximum degree usedin the machine, which corresponds with the position of the parts inFigs.

6 and '7.

As set forth in my previous applications, the mechanism herein used is astraight-line motion mechanism in which circular eccentrics are usedthat are mounted one inside the other and which occupy the entire spaceinside the element next outside of it. The outside eccentric of thesecondary assembly fills the entire space inside its yoke 60!. Withcircular eccentrics so embraced, I have found that adjustment of the twoeccentrics forming the primary assembly by means of turning the screwshaft 102 will cause the secondary assembly to adjust its eccentricityautomatically to equal that of the primary. This, of course, simplifiesthe mechanism needed and only manual adjustment of the primary assemblyis necessary to cause the entire apparatus to be adjusted to the newsetting. (It is fundamental in straight-line motion mechanism thatcircular eccentrics be used inside one another with the lift of theprimary and secondary means at all times equal.) I have found that thisadjustment takes place in spite of the fact that one part of thesecondary assembly rotates in one direction and the other part in theopposite direction. The mechanism shown in the drawings, however, doeshave dead center at the top and bottom positions of the rotor and forthose positions it is advisable to provide means insuring that thedirection of rotation of the eccentrics does not change. Thus it ispossible at those dead center positions for the secondary assembly to gointo greater or lesser lift positions. I have devised the followingnovel means of preventing this and overcoming other objections whichwill be mentioned as the description proceeds. In the first place, theouter eccentrics of the secondary assembly are kept in equi-angularrelation to each other by the articulating means which will be describedhereinafter, so that a common point on one, in the case of the mechanismshown in the drawings, is 120 away from the corresponding point at theneighboring outer eccentric, regardless of the position that any suchouter eccentric is in with relation to the lobe of its inner eccentric.I also find that it is useful for the proper functioning of themechanism to have the equal radial disposition of the cylinders aboutthe periphery of the rotor. The fixed relation of the three lobes of theinner eccentric of the secondary assembly also performs a function inproper operation of the device, and with these features each secondaryunit is helped past its dead center position by the other two units, andthe adjustment of the eccentricity of any secondary unit to equal theadjustment of the primary assembly takes place automatically whether thepump is standing still or operating.

If we were dealing with a construction in which there was only one yokeGill and one outer secondary eccentric, the secondary assembly wouldhave to be adjusted simultaneously with the primary assembly by meansconnected to the secondary.

It will be obvious from the description heretofore given that the rotorturns in a clockwise direction as viewed in Fig. 5 and that as a resultof that turning the pistons move radially back and forth in theircylinders between the bottom and top positions shown in Fig. 7. At thebottom and top positions the periphery of the rotor is in contact withfiller pieces 504, 405 which present curved contact faces to theperiphery of the rotor. As can be seen by comparing the positions of theparts in Fig. 7 and in Fig. 8, this separating of the plates around theperiphery of the rotor inside the casing in the two parts makes itpossible to give apumping action. As seen in Fig. 7, for example, thereis a space outside between the rotor and the inside of the casing whichis tapered from the inlet port 406 toward the filler pieces 494, 495,and the tapered structure exists between the filler pieces and thedischarge outlet 467. It is believed that the operation of the devicewill be obvious from the description heretofore given, but it is desiredto point out that the direction in which the liquid is pumped can bechanged if the adjustment of stroke above described is carried to theopposite side of the zero position (pump center) shown in Figs. 1, 2, 4and 5. Thus if the block 104 were screwed upwardly instead ofdownwardly, the torsion shaft it! would be moved in a straight line tothe other side of pump center, causing the top piston in Fig. '7 to goto the top point of its stroke. It will be seen that there would beliquid in the cylinder as it is cut off from the discharge outlet dillby the filler piece 405 and that the subsequent movement of the cylinderwould carry it into contact with the port 306 which theretofore was theintake port, and the piston would push the liquid out into that port.The effect of changing the timing of the pistons in this manner in apump is to make it possible to change the direction in which the liquidis being pumped, without stopping the rotation of the drive shaft atall. The advantages and uses of such a construction will be obvious.This is especially true when it is taken in connection with the factthat the output of the pump can be varied. Similarly through a hydraulictorque converter the speed or direction of rotation of the drive shaftof the fluid motor can be varied. In other words, by simply changing thesetting of the two eccentric elements of one of the eccentric assembliesin the mechanical movement, it is possible to go to any other portion ofa complete cycle of movement.

Stated another way, my invention provides mean whereby a full stroke inone direction can be changed to zero stroke, passing through the zeropoint into a full stroke in the opposite direction while the machine isoperating, without changing or altering the position of the drivingmeans itself. In. this statement I am assuming that we are dealing witha pump of the type mentioned in the opening of the specification; and bydriving means I refer to the drive shaft. The same principle will applyin the case of an engine.

There i another novel feature shown in the drawings. This is thearticulation. As above mentioned, it will be noted that the outerelements of the secondary eccentric assembly for each piston element arefree and independent of each other. (I have already pointed out thatthey have no fixed connection to the other elements of the secondaryeccentric to which each one belongs.)

In placing three outer secondary cams upon a shaft consisting of threeinner secondary cams at 120 relation to each other, these outersecondary cams must bear a constant rotational relation to each other atall times to insure the operation of the variable assembly. Thus wherethere are three outer secondary cams they should always b at 120relation to each other, regardless of how the stroke resulting from theentire secondary assembly is varied. Owing to the fact that the lobes ofthe three outer elements of the secondary eccentric are set 120 apart,so that the outer eccentrics are turning about different centers, thereare no points on the complemental faces of any two of the outereccentrics opposite each other which remain in fixed relation to eachother when the lift of the secondary eccentric is changed.

I have shown in Figs. 9, and 11 a form of means for articulating theouter secondary cams so that they are always 120 apart, regardless oftheir relation to the inner secondary cams, this mechanically preferableconstruction involving the use of diiferential disks and cranks. Thus inthe side view of Fig. 10 the three secondary cams Hil, HI, H2 havedifferential disks H5 located between them which are free to rotate onthe inner secondary member about the common center of that innersecondary member. These articulating differential disks rotate inrelation to the inner secondary cam assembly one full revolution forevery full revolution of the inner secondary eccentric member. tation isnot at a uniform rate, its variable speed is governed by the relation ofthe cams with which it is joined by the cranks H6. This can be seen fromFigs. 9 and 11. These cranks H6 are able to swing radially outward atone end as the diameter of the path of the outer secondary camsincreases. It will be observed that there is a crank H6 from each cam tothe adjacent diiferential disk I I5, and another crank from thedifferential disk to the cam ring eccentric 0n the other side or thedisk. This construction takes care of itself automatically and keeps thelifts equal. The connections between disks and the eccentrics arenecessary because the points of connection are not at the points ofintersection of the lift lines of the two eccentrics, nor are they incommon relation to the center lift line.

It will be seen that the pump which I have described i one which has nooperating crank, and that I hav produced a variable pump in which twosets of two eccentrics each, with equal effective lift, by workingsimultaneously in oposite directions provide reciprocation of a thirdmember, but at the same time the individual assemblies of the sets ofeccentrics are variable at will with relation to each other in a verysimple manner while the pump is working. It is always possible to varythe stroke and keep th effective eccentricity of one assembly to theother equal, as is necessary in a device of this type.

What I claim is:

1. In a straight-line mechanism for converting rotary motion to or fromreciprocatory motion, a primary eccentric assembly comprising two co-While its rois operating circular eccentrics and means for adjustingsaid eccentrics to vary the lift caused thereby and for locking thesetwo eccentrics in adjusted positions a secondary eccentric assemblyacted upon by said primary eccentric assembly and comprising a unitaryinner member having a plurality of eccentric lobes side by side spacedaround the member equi-angularly and an outer eccentric on each lobe andmeans associated with the secondary assembly keeping said outereccentrics spaced apart equi-angularly; reciprocating elements embracingsaid outer eccentrics and means guiding said reciprocating elementswherebyrelative rotation of the primary and-secondary assemblies inopposite directions causes conversion of motion, and adjustment of thelocking means varies the lift of both primary and secondary assembliesequally.

2. In a straight-line harmonic motion mechanism for converting rotarymotion to or from reciprocatory motion, driving and driven connections,cooperating primary and secondary eccentric assemblies and reciprocatoryelements embracing the secondary eccentric assembly, said primaryassembly comprising a pair of co-operating circular eccentrics and meansadjustably controlling the relation of the two eccentrics relatively toeach other, thereby controlling the lift of the assembly; said secondaryassembly engaging said primary eccentric assembly and comprising aplurality of circular inner eccentrics in fixed equi-anguiar relation toeach other about a common axis but lacking rigid connection to any otherpart of the machine, an outer circular eccentric surrounding each suchinner eccentric and surrounded in turn by one of the driven or drivingconnections and means for guiding said connections in equi-angularlyspaced paths of reciprocatory movement, whereby when the lift of theprimary assembly is adjusted the secondary assembly automaticallyassumes equal lift.

3. In a straight-line harmonic motion mechanism for converting rotarymotion to or from reciprocatory motion the combination of primary andsecondary circular eccentric assemblies of equal lift adapted to act oneon the other, the primary of said eccentric assemblies comprising twoco-operating circular eccentrics and means associated with said primaryeccentric assembly adjustably controlling the lift, the secondary ofsaid eccentric assemblies lacking rigid connection to any other part ofthe mechanism and comprising a unitary element engaging said primaryeccentric assembly and having a plurality of eccentrics rigidly fixedside by side with their lobes in equi-angular relation to each otherabout a common axis, a circular eccentric on each such lobe and areciprocatory element surrounding each such eccentric, means guidingsaid reciprocatory element and means maintaining each eccentric on saidlobes in fixed angular relation to the other eccentrics on said lobes,whereby when the lift of the primary eccentric assembly is changed byits adjustable control, the secondary assembly automatically equalizesits lift to that of the primary assembly.

4. In a straight-line harmonic motion mechanism for converting rotarymotion to or from reciprocatory motion, primary and secondary pairs ofco-operating circular eccentrics, means adapted to lock the primary pairof eccentrics together, said means also being adapted to adjust the liftof the said pair of eccentrics by rotating them in opposite directions,the secondary pair of eccentrics comprising an inner group of eccentricswith anagooa lobes arranged in fixed equi-angular relation to each otherabout a common axis and engaging one of said primary pair ofeccentricsand an outer eccentric group'consisting a circular eccentric surroundingeach lobe of the inner eccentric group, in combination with a driving ordriven connection embracing each outer eccentric, and means guiding saidconnections in equi-angularly spacedpaths of reciprocatory movementwhereby when the lift of the primary assembly is adjusted the secondaryassembly automatically equalizes its lift.

5. In a straight-line reciprocating mechanism adapted to'change rotarymotion to or from reciprocatory motion, the provision of four circulareccentrics forming cooperating eccentric assemblies consisting of pairsof adjacent eccentries, the reciprocatory motion being functionallyapplied'or received at the periphery of one of said eccentrics, saidpairs of adjacent eccentrics being constructed and arranged to haverelatively opposite rotation as'units to give the conversion of motionto' or from reciprocatory motion, and

means adapted to cause movement of the two eccentrics of said pairsequally in' opposite directions with relation to each other for thepurpose of changing the length of the reciprocatory movement.

6'. In a straight-line reciprocating mechanism for converting rotarymotion to or from reciprocatorymotion, a primary eccentric assembly ad'-justabl'e as to its lift, a secondary or outer eccentric assemblycomprising an inner member having a plurality of eccentric lobes side byside spaced around a center in fixed equi-angular relation, and an outereccentric on each lobe, in combination with articulating means linkingsaid outer eccentrics together in equi-angular relation 12 at all times,whereby the secondary assembly is maintained in proper timed relation.

7'. In a straight-linereciprocating mechanism for convertingrota-ry'motion to or from reciprocatory motion, aprimary eccentricassembly adjustable as to its lift, a secondary or outer eccentricassembly comprising an inner member having a plurality of eccentriclobes side by side spaced arounda center in fixed equi-angular relation, and an outer eccentric on eachlobe, in combination' with meansadapted to cause movement of theinner and outer eccentrics of thesecondaryassembly with relation toeach other for thepurpose'of changingthe lift of thesecondary assembly, and articulatingmeans holding saidouter eccentrics together in'equi-angular relation when the-eccentricsare-rotating oppositely to the inner secondary member to change thelift.

8; In a straight-line mechanism for converting rotary motion to or fromreciprocatory motion, the provision of four co-operating circulareccentrics forming primary and secondary eccentric assemblies of 'pairsof'eccentrics with 'said secondary eccentric assembly surrounding saidprimary eccentric assembly, a yoke surrounding an eccentric of saidsecondary assembly to and from which eccentric the reciprocatory motionis given or received, means guiding thereciprocatory movements of saidyoke in combination with adjustable control means adapted to-adjustthe-relative-positions of theprimary pair of eccentrics to each otherand of the secondary pair of eccentrics to-each other and thereby adjustthe lift, whereby the application of motion to the yoke willcauserotation of one pair with a lift equal tothe lift ofthe-other pairof eccentrics.

TOM H. THOMPSON.

